Understanding BBB stroke pathophysiology is critical since stroke is a leading cause of death and disability and increased cerebrovascular permeability is an important factor for the development of ischemic brain damage and edema formation. Vasogenic brain edema, due to a BBB opening is the type of edema that is present in the brain after injury induced by a cerebrovascular accident. Vasogenic brain edema can result from opening of tight junctions at the BBB or an increase in pinocytotic activity. Damage to the BBB from ischemia/stroke can result in poor clinical outcomes during stroke recovery, such as vasogenic brain edema and inflammation. In addition, changes in BB transport characteristics may influence the transport of clinically useful medications used to either treat the ischemic episode or medicate other disease stages. Our major hypothesis is that hypoxia/aglycemia and reperfusion (associated with stroke) alters both the expression of BB specific proteins and the permeability and transport of critical solutes across the BBB, thereby contributing to the development and severity of stroke. To investigate this hypothesis, our major objective and specific aims are to investigate and quantify the effect of hypoxia/aglycemia/reoxygenation on the endothelial cells of the BBB by quantifying effects on cell resistance, permeability, tight junctional protein/cytoskeletal protein expression and transcriptional/post-transcriptional expression of specific proteins associated with hypoxia. We will also identify the role in calcium in hypoxia/aglycemia/reoxygenation and determine the role of astrocytes. The techniques we will use are both in vitro and in situ coupling our experience of analytical biochemistry and vascular biology in a focused program to study the effect of hypoxic/aglycemic stress on endothelial cells of the BBB.